Long‐term variations in global sea level extremes

Abstract

Decadal to multidecadal variations in sea level extremes unrelated to mean sea level changes have been investigated using long tide gauge records distributed worldwide. A state space approach has been applied that provides robust solutions and uncertainties of the time evolving characteristics of extremes, allowing for data gaps and uneven sampling, both common features of historical sea level time series. Two different models have been formulated for the intensity and for the occurrence of extreme sea level events and have been applied independently to each tide gauge record. Our results reveal two key findings: first, the intensity and the frequency of occurrence of extreme sea levels unrelated to mean sea level vary coherently on decadal scales in most of the sites examined (63 out of 77) and, second, extreme sea level changes are regionally consistent, thus pointing toward a common large‐scale forcing. This variability of extremes associated with climate drivers should be considered in the framework of climate change studies.

Spatial and Temporal Variability and Long-Term Trends in Skew Surges Globally

“…However, despite strong correlations between some regions around the North American coastline and across the Atlantic to the North Sea, none of the correlations are significant at the 95% level. Just prior to completing our study, we learnt of a similar investigation by Marcos et al (2015). Using the GESLA dataset, they showed that the intensity and frequency of ESL unrelated to MSL display a regional coherence on decadal time-scales.…”

“…Using the GESLA dataset, they showed that the intensity and frequency of ESL unrelated to MSL display a regional coherence on decadal time-scales. Their finding points toward large-scale climate drivers of decadal changes in storminess (Marcos et al, 2015). The string correlations between neighboring sites show that these large scale climatic drivers are important, but there significance is difficult to assess in relatively short datasets have a high degree of temporal autocorrelation.…”

“…This dataset was originally collated by staff from the National Oceanography Centre (NOC) in the UK and the Antarctic Climate and Ecosystems Cooperative Research Centre (ACECRC) in Australia. The GESLA dataset has primarily been used to assess changes in ESL (e.g., Woodworth and Blackman, 2004;Menéndez and Woodworth, 2010;Hunter, 2012;Hunter et al, 2013;Marcos et al, 2015) but has also been used to evaluate changes in the tides (Woodworth, 2010;Mawdsley et al, 2015).…”

“…Furthermore, few studies have examined the spatial coherence in storm surge variability along stretches of coastlines and between regions. This is despite the fact that regional climatic variability can account for much of the inter-annual and multidecadal variability in storm surges (Marcos et al, 2015;Wahl and Chambers, 2016).…”

Long-Term Trends and Variability of Water Levels and Tides in Buenos Aires and Mar del Plata, Argentina

“…In most areas of the world, secular changes in extreme WLs over the last century have been found to be of similar magnitude as the rise in MSL (see e.g., Woodworth and Blackman, 2004;Menéndez and Woodworth, 2010). In recent years some studies have additionally identified significant secular trends in both tide and surge components in many regions of the world (Marcos et al, 2015;Mawdsley et al, 2015, for global analyses). However, a better understanding of the links between atmospheric dynamics and extreme WLs variability is needed in order to better model their occurrence probability (see e.g., Cid et al, 2015).…”